[R] R function similar to gradient function in Matlab?

[Ranjan Maitra]

Hi,

I am trying to convert some Matlab code into R for running some
experiments and I was wondering if there is some function in R which
does the work of the gradient function in Matlab calculating the
"gradient" of 1-, 2- and 3-d images. I only need the 3-d calculations
for running these experiments.

Many thanks and best wishes,
Ranjan